Frustrated by Telkom contract

I took a contract with Telkom Mobile and ported my old number over to them. Phone was working fine at first but for the past 6 weeks I have been having a problem with incoming calls that are being rejected.

I have phoned telkom call centre six times and firstly they said I had barring on my phone and was given USSD to cancel. That did not work and called again and was given a different USSD of which was not working on my phone. For the third call I was told the number was not properly ported and they will relay their porting department to fix and I must wait 48 hour for that to take effect. After 3 days without any change I called again and this time was told the matter would be escalated and must wait 72 hours for a resolution. This was 7 days ago and still some of my incoming call are not coming through.

I can't be paying for service I am not receiving so I am pleading with Telkom to cancel my contract if they can't provide the service or fix this issue.